The present invention relates to a method for sharing internal excess bandwidth between output and input termination modules of a switching network, to a switching network and more specifically a broadband switching network for applying such a method and to a communication network including such a switching network.
It relates more specifically to networks having a multipath self-routing switch fabric and means for distributing bandwidth between connections of different termination modules.
It is assumed that, in such a network, incoming traffic is waiting in the input termination modules to be transferred to the output termination modules via the switch fabric. This switch fabric is preferably made of modular switching elements with each a small internal buffer memory.
The available resources corresponding to the available bandwidth on the links between output termination modules and switch fabric and on the links between switch fabric and input termination modules, are allocated by a connection admission control CAC function for connections to be provided with a guaranteed bandwidth and by an internal distributed rate based flow control IDRFC function for the allocation of the available internal excess bandwidth to other connections. This IDRFC function is based on a distributed arbiter function, which periodically renegotiates the excess bandwidth allocation between output and input terminations modules at the level of which it is located.
Till now such an IDRFC function has no means for taking account of the level of quality of service required for a specific flow to be transmitted by means of a connection which is not under control of the CAC function. Consequently, network operators do not have any means for applying a Quality of Service policy corresponding to their needs to dynamically share the internal excess bandwidth between input and output termination modules of a broadband network controlled as indicated above.